High pressure portable tube bender

ABSTRACT

This invention relates to an improvement on U.S. Pat. No. 3,336,779 wherein a plurality of control cams are provided for progressive operative engagement of pawls carried thereon with a control rack gear to aid in obtaining high pressure bending movements in the apparatus. A pressure transmitting shoe engages with the tube to aid in retaining it in the apparatus and to aid in applying pressure to the tube as it is being bend. A handle or other drive means operatively engages a shaft on a carrier frame for cam actuation.

United States Patent Schall et a1.

HIGH PRESSURE PORTABLE TUBE BENDER Inventors: Wallace J. Schall, 1101 17th St., N.W.; Richard F. Van Horn, 921 14th St., N. W., both of Canton, Ohio 44703 Filed: Oct. 13, 1972 Appl. No.: 297,232

US. Cl. 72/149, 72/218 Int. Cl B21d 7/04 Field of Search 72/217, 218, 219,

References Cited UNITED STATES PATENTS Reynolds 72/150 X 1 Jan. 15, 1974 3,336,779 8/1967 Schall .1 72/217 1.762234 6/1930 Matthews 72/218 2,569,544 10/1951 Tal 72/219 Primary Examiner-Milton S. Mehr Attorney-Vern L. Oldham et a1.

[5 7 ABSTRACT This invention relates to an improvement on Us. Pat. No. 3,336,779 wherein a plurality of control cams are provided for progressive operative engagement of pawls carried thereon with a control rack gear to aid in obtaining high pressure bending movements in the apparatus. A pressure transmitting shoe engages with the tube to aid in retaining it in the apparatus and to aid in applying pressure to the tube as it is being bend. A handle or other drive means operatively engages a shaft on a carrier frame for cam actuation.

7 Claims, 10 Drawing Figures PAIENTEBJAN 1 5 I974 SHEUIUF3 PATENTEO mu m 3.735.190 arm 3 or 3 {"TOOTH POSITION WITH OUTER PAWL AT MAX.

TOOTH POSITION WHEN MIDDLE PAWL REACHES MAX.

NEW POSITION OF TOOTH WHEN INNER PAWL REACHES MAX.

1 HIGH PRESSURE PORTABLE TUBE BENDER This invention relates to tube benders, and especially to a high pressure portable thin wall tube bender for smoothly curving tubes by manually applied forces.

BACKGROUND OF INVENTION This invention relates to portable tube benders of the type as shown in my prior US. Pat. No 3,336,779 issued Aug. 22, I967 upon a Portable Tube Bender. While my previous type of a tube bender has been satisfactory for many uses, it is desirable to bend relatively large diameter tubes in some instances and quite high pressures are required for proper bending actions thereon.

It also has been somewhat difficult in use of my prior type of apparatus to have effective bending forces exerted on larger sized tubes without undesirably deforming the same. Also, the use of higher tube bending pressures has been desired for larger diameter tubes.

The general object of the present invention is to provide a new and improved tube bender apparatus particularly characterized by the high pressure bending forces set up therein by a novel cam and pawl force unit provided in the apparatus and by the provision of more pressure in radial direction for bending action.

Another object of the invention is to provide a portable tube bending apparatus wherein high pressure can be progressively created by bending means provided in the apparatus and wherein a plurality of strokes of an operating handle can be accumulated in the apparatus to build up bending pressures therein.

A further object of the invention is to isolate a tube being bent from the actual bending means and to transmit bending pressures thereto operatively through enclosure means positioning the tube in the apparatus.

Another object of the invention is to provide a tube bender apparatus in which a tube can be readily positioned for bending action and wherein the apparatus permits ready engagement with a tube.

The foregoing and other objects and advantages of the invention will be made more apparent as the specification proceeds- Attention now is particularly directed to the accompanying drawings, wherein:

FIG. 1 is a side elevation of the apparatus of the invention in operative engagement with a tube;

FIG. 2 is a fragmentary vertical section taken on line 2-2 of FIG. 1;

FIG. 3 is a fragmentary vertical section taken on line 3-3 of FIG. 1;

FIG. 4 is a fragmentary section showing the several control cams in the apparatus and the spring or release action thereof;

FIG. 5 is a diagrammatic sectional view of the individual cams and the positioning thereof in the apparatus;

FIG. 6 is a fragmentary end elevation showing the control cams in the apparatus;

FIG. 7 is a diagrammatic view of a control cam and pawl and its maximum movement in the apparatus in relation to the rack gear; and

FIGS. 8, 9 and 10 are progressive views showing the action of the cams and pawls in providing the frame motion for tube bending action.

When referring to corresponding members shown in the drawings and referred to in the specification, correspending numerals are used to facilitate comparison therebetween.

INVENTIVE SUBJECT MATTER As one embodiment of the invention, a portable tube bender including a semi-circular shaped frame having a gear rack on its inner circumference and a semicircular shaped recess on its outer periphery, a twopiece pivotal linkage means pivotally mounted at one end of the frame by one end of the linkage means, and a pressure plate member with a semicircular shaped axially extending recess on its inner surface for engaging the outer periphery of the frame are provided. A roller means is mounted on the free end of a linkage member for engaging the pressure plate on its outer surface and maintaining it in good contact with the frame, a plurality of individual cam and pawl means are rotatably mounted on the linkage means and engage the gear rack on the frame to provide for advancing a portion of the linkage means, and means for rotating the cam and pawl means to provide a bending action on a tube received between the pressure plate and the frame, as the portion of the linkage means is advanced.

Reference now is directed to the details of the structure shown in the drawings, and a tube bender of the invention is indicated as a whole by the numeral 10. This tube bender 10 includes an arcuate frame means or bar 12 which has a concave recess 14 on its outer surface and which has a rack gear 16 formed on the radially inner surface thereof. An operative bending force producing means such as a two piece linkage system is operatively carried by the frame 12 and it includes a pair of links 18 and 20 pivotally secured at one end to a pin or rod 22 extending through an end portion of the frame 12 and at the opposite ends of the links a second pair of side bars or links 24 and 26 are pivotally carried by a pin 25. The pin 22 also engages a U-shaped clamp bracket 21 which slidably carries a clamp shoe 30a therein. The bracket 21 is carried at an end of the frame 12 to engage an end of the tube between the frame and the clamp shoe 30a as the bracket extends outwardly from the frame. A cam means 29 is journalled on the bracket 21 to lock or. release the clamp shoe 30a in relation tothe tube 32. An end 2941 of the cam is exposed for manual control of its position.

The tube bending forces are provided by movement of the links or side bars 24 and 26 with relation to the frame. These side bars 24 and 26 are positioned adjacent lateral margins of the frame 12 and have ends that extend radially therefrom to position a roller 28 operatively on a shaft or pin 27 on the radially outer side of the frame, as hereinafter described. This roller 28 bears on a straight elongated clamp shoe 30 which in turn operatively engages a tube 32 introduced into and operated on by the apparatus of the invention to provide a bend therein. The links 18 and 20, and 24 and 26 are connected at the center of the arcuate frame 12, while the individual operative links or bars 24 and 26 apply the actual operative bending forces to the tube by progressive step by step movement of the bars 24 and 26 away from the links 18 and 20, as hereinafter de scribed.

These bars 24 and 26 have a pressure producing shaft 38 joumalled thereon, as by bearings 40, and extending therebetween whereby the shaft 358 can be turned or rotated with relation to its carrier means. To provide a high leverage force applying means for the shaft 38, a

suitable handle 42 having bifurcated end portions 44 is suitably secured to the shaft 38 and protrudes therefrom whereby one can manually move the handle 42 through force producing arcs. Conventional ratchet means 46 are provided in the connection of the handle to the shaft 38 so that the handle will only advance the shaft in one direction.

The shaft 38 also aids in supporting the arcuate frame 12 as by a roller or ball bearing 48 carried by the shaft 38 and engaging the inner surface of the frame 12. Preferably a recess 50 is formed on an axial center line of this frame and the teeth of the rack 16 are formed on each side of such recess. The bearing 48 seats in the recess 50.

Naturally, prior to obtaining any bending action on the tube, the tube is brought into engagement with the arcuate recess or face 14 of the frame 12 with the bars 24 and 26 positioned adjacent the links 18 and 20. Also, the force transmitting or clamp bar 30 is brought into engagement with the outer portion of the tube. This bar 30 has a concave recess 54 formed on its inner surface and which recess is complementary to the recess 14 so that full peripheral engagement with the tube is obtained by the apparatus. Relative movement between the frame 12 and the arms 24 and 26 is facilitated by the roller 28 that is journalled on the ends of the bars 24 and 26.

The actual force transmitting means and generating means in the apparatus include, in this instance, three sets of aligned cams 58, 59; 60,61; and 62 and 63 with one set of earns 58, 60 and 62 being on one side of the bearing 48 and with the other set of earns 59, 61 and 63 being on the opposite side of the bearing 48 as shown in FIG. 3. These cams are identical except that they have key slots indicated at 64, 65 and 66 provided in 120 spaced relationship to each other in relation to the eccentric contour of the cams, all as indicated in FIG. of the drawings. Hence, a common keyway is provided in the shaft 38 and a key 68 then is used for securing all of the cams in position. Corresponding cams on the opposite side of the bearing are positioned in the same manner in relation to the axis of the support shaft 38.

The remaining force transmitting elements in the apparatus comprise inner pawls 70 and 70a positioned on the inner cams 58 and 59, middle pawls 72 and 72a carried by the middle cams 60 and 61 and outer pawls 74 and 74a operatively carried on the axially outer earns 62 and 63. These pawls are provided with different operative length fingers extending therefrom and for example with a shorter finger 71 being provided on the inner pawl 70, a slightly longer finger 73 being provided on the pawl 72 and the longest operative finger 75 being provided on the outer pawl 74. These pawls 70, 72 and 74 are all free to rotate with relation to the cams on which they are positioned. However, as the cams are rotated with the shaft 38, then the pawls are forced to move radially with relation to the shaft 38 and this causes the fingers 71, 73 and 75 to progressively engage with the different individual teeth 17 on the rack gear for progressively causing movement of the bars 24 and 26 and associated means in the direction of the arrow 76 shown in FIG. 1.

FIGS. 8, 9 and show the relative positions of the pawls and their operative fingers as the frame 12 is forced to the left. FIG. 8 shows how cam 63 forces the pawl fingers 75 to engage a rack gear tooth 16a to force the frame 12 to the left and then how the fingers 73 and 71 successively are brought into engagement with such tooth 16a for further frame movement. By such time, the cam 63 has moved the pawl 74 to the right so that the finger 73 drops down by one of the springs 92 acting thereon to engage the next tooth 161), FIG. 10. Likewise, the other cams and pawls are progressively actuated to continue the force cycles.

FIG. 4 shows that the various pawls 70, 72 and 74 each have an edge bracket or flange 80 thereon to which a member, such as a clevis or similar device 82 is pivotally secured by a pin 84. This clevis positions an end ofa center rod or pin 86 and with the opposite end of the pin engaging an aperture 88 provided in the support bar or plate 90 carried by and extending between the bars 24 and 26. A spring 92 is carried by each of these pins 86 and urges the pawl to remain in an off center operative position, as shown in FIG. 4. However, when these springs 92 are compressed, the individual pawls can be moved over a dead center position so that the fingers thereof are brought out of operative engagement or relationship with the rack gear 16 on the frame. Hence, the bars 24 and 26 and associated means can be moved through any desired arc to release the tube bender 10 from an engaged tube.

It is by the progressive engagement of the individual fingers 71, 73 and 75 of the pawls with the teeth of the rack gear that a progressive bending action can be produced on the tube by the increments of movement in the apparatus by rocking the handle 42 to the right that turns the shaft 38 to provide arcuate movement of the frame or means 12 along a tube with resultant bending thereof because of the pressure engagement between the clamp bar 30 and the remainder of the apparatus in relation to the tube being bent. The apparatus provides a great mechanical advantage in the forces transmitted to the tube by the pawls from the handle 42.

FIG. 3 of the drawings clearly shows that the adjacent portions of the clamp bar and frame are contoured complementary to each other and engage snugly with the entire periphery of the tube being processed. I

The apapratus of the invention is of a sturdy design, but yet is of relatively light weight. Hence, the apparatus can be moved from place to place readily and can be used for providing a smoothly contoured bend or curve in a tube of the size for which the apparatus is designed to operate.

In making the apparatus of the invention, it should be noted that the cams 58, 60, 62, etc. and the pawls 70, 72, 74, etc. must be made from quite hard metal or made of proper metal and size to carry the load applied thereto. It also should be appreciated that other means rather than the handle 42 and ratchet 46 can be used for driving the mechanism. For example, the hexagonal or other shaped end on the shaft 38 can be engaged with an impact wrench, a drill motor chuck, or equivalent means for driving this shaft to provide the force required in the bending action.

It will be seen that in the bending action obtained, the bars 24 and 26 stay in one position, and the remainder of the assembly moves laterally in the direction of the arrow 76, as indicated.

For example, in bending a 2 inch tube, it has been found that the teeth 17 on the gear rack 16 should be one-half inch on centers, and then the difference in lengths between the pawl fingers 71,- 73 and 75 would be a maximum of one-eighths inch. Likewise, the difference in radial length of the cams 58 et al is fivesixteenths inch in what the cam is off center so that in a rotation thereof, one can obtain a throw of five thirtyseconds inch. In the actual bending action, it is seen, as shown in FIGS. 8, 9 and 10, that the shorter pawl finger 75 has been moved to engage a new tooth before the longer pawl finger 71 has disengaged from the prior tooth.

Obviously, the pawls and pawl fingers set up some appreciable compressive strain engaging the tube 32 in the apparatus, but with the maximum forces generated by the pawls, when engaged with the rack teeth, being to move the rack and associated means in a circumferential direction. It is believed that as much as tons pressure can be set up in the apparatus of the invention when adapted to bend 2 inch conventional tubing.

It should be noted that the roller 28, as shown in the drawings, normally is positioned on pair of cams 28a which are adapted to be rotated about 180 for example to bring this roller into operative engagement with the frame bar 30, and with such cams being adapted to be pinned to the ends of the bars 24 and 26 to be operatively positioned. The pins 128 can engage holes 130 formed in the cams to bring them up for pressure engagement with the bar 30. Thus, for article release action, the pins 128 would be released and the cams 28a are disengaged by pulling the clamp bar 30 to the right as shown in the drawings. This will release the clamp bar and tube.

If required, any suitable type of a disc shim can be used between the cams and the ring pawls to retain such pawls in proper position on the periphery of the cams and prevent any axial misalignment therebetween.

The rack gear 16 can be made in any suitable manner, as by being formed in a metal block or in an insert adapted to be attached to a frame member, and the teeth can protrude, as indicated in the drawings, or be recessed for maximum strength, as desired.

The radial offsets in the cams 58, 60 and 62 and the lengths of the pawl fingers 71, 73 and 75 are coordinated with thepitch of the teeth on the gear rack 17 as to cause the cam and pawl action to advance the apparatus for tube bending as shown and described. The forces generated by the cams and pawls produce high pressures moving the frame 12 arcuately.

While one complete embodiment of the invention has been disclosed herein, it will beappreciated that modification of this particular embodiment of the invention may be resorted to without departing from the scope of the invention.

What is claimed is:

1. In a tube bending apparatus, the combination of a semi-circularly shaped frame having a gear rack on the inner circumference thereof and a semicircularly shaped recess around the outer circumference thereof,

a two-part pivotal linkage means pivotally mounted by one part to one end of the frame and pivotal in the plane thereof,

a pressure plate member with a semi-circular shaped axially extending recess on its inner surface,

a device mounted at the free end of the linkage means to engage the outer surface of the pressure plate member, the recess on said member mating with the recess in the frame to define a substantially circular shape in which a tube can be re ceived,

a plurality of cam and pawl means rotatably mounted by the linkage means so as to engage teeth of the gear rack on the inner circumference of the frame, and

means to rotate the cam means whereby the pawls progressively engage teeth on the gear rack and force part of the linkage means to move to bend a tube received between the frame and the pressure plate member.

2. In a tube bending apparatus, the combination of an arcuate shaped frame defined by an imaginary central point having a semi-circularly shaped recess on the outer circumference thereof,

a gear rack on the frame and extending alongthe inner circumference thereof,

a linkage means pivotally mounted at the imaginary central point defining the base frame and said linkage means being pivotal in the plane of the frame,

a pressure plate for engaging the outer surface of the frame and having a semi-circular recess on its inner surface.

a roller rotatably mounted on the free end of the linkage means so as to rollably engage the outer surface of the plate, the recess in the plate mating with i the recess in the frame to define a substantially circular shape,

a plurality of cam means rotatably mounted by the linkage means and carrying pawls for progressively engaging the gear rack on the inner circumference of the frame, the roller being held in position on the pressure plate on the outer cicumference of the frame, and

three identical cams being provided and being positioned in about offset relation to each other on a common. carrier shaft,

means to rotate the cam means whereby the pawls force the frame to move and the roller is forced to move around the outer circumference of the frame to effect a bending action on a tube received between the frame and the pressure plate.

3. In a tube bending apparatus as in claim 1, the pro vision of a support shaft carried by the linkage means for the cam and pawl means, a plurality of identical cams, means securingthe cams to the support shaft in balanced offset relation, a pawl means being carried by each of said cams, and the different pawl means having fingers thereon of slightly different lengths.

4. In a tube bending device as in claim 1, the improvement comprising said device being mounted on cam means and having an operative and an inoperative position.

5. In a tube bending device as in claim 2, the improvement comprising said pawls having a center bore engaging said cam means, re-leasable means urging said pawls to operative positions engaging said gear rack.

6. In a tube bending apparatus as in claim 2, the provision of a support shaft carried by the linkage means for the cam and paw] means, means securing the cams to the support shaft in balanced offset relation, and the different pawl means having fingers thereon of slightly different lengths.

7. In a tube bending apparatus as in claim 3, the cam and paw] means being'coordinated with each other inrelation to the pitch of the gear rack teeth so that one revolution of a cam will cause the pawl means thereon to advance into engagement with another tooth on the gear rack.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3,785,190 I Dated Jan. 15, 1974 Inventor(s) Wallace J. Schall t 1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Abstract, line 8 "bend should be bent Column 1, line 27, "pressure" should be pressures Column 4, line 42;, "apapratus" should'be apparatus Column 4, line 51, before "made", insert are Column 5, line 62, semi-circular should be semi-circularly Signed and sealed this 23rd day of April 1971 J (23mm) Atteat:

EDWARD I-I.FLETCIIER,JR. MARSHALL DAMN Atte sting Officer Commissioner of Patents F QF M PO-1OSO (10-69) 

1. In a tube bending apparatus, the combination of a semi-circularly shaped frame having a gear rack on the inner circumference thereof and a semi-circularly shaped recess around the outer circumference thereof, a two-part pivotal linkage means pivotally mounted by one part to one end of the frame and pivotal in the plane thereof, a pressure plate member with a semi-circularly shaped axially extending recess on its inner surface, a device mounted at the free end of the linkage means to engage the outer surface of the pressure plate member, the recess on said member mating with the recess in the frame to define a substantially circular shape in which a tube can be received, a plurality of cam and pawl means rotatably mounted by the linkage means so as to engage teeth of the gear rack on the inner circumference of the frame, and means to rotate the cam means whereby the pawls progressively engage teeth on the gear rack and force part of the linkage means to move to bend a tube received between the frame and the pressure plate member.
 2. In a tube bending apparatus, the combination of an arcuate shaped frame defined by an imaginary central point having a semi-circularly shaped recess on the outer circumference thereof, a gear rack on the frame and extending along the inner circumference thereof, a linkage means pivotally mounted at the imaginary central point defining the base frame and said linkage means being pivotal in the plane of the frame, a pressure plate for engaging the outer surface of the frame and having a semi-circular recess on its inner surface. a roller rotatably mounted on the free end of the linkage means so as to rollably engage the outer surface of the plate, the recess in the plate mating with the recess in the frame to define a substantially circular shape, a plurality of cam means rotatably mounted by the linkage means and carrying pawls for progressively engaging the gear rack on the inner circumference of the frame, the roller being held in position on the pressure plate on the outer cicumference of the frame, and three identical cams being provided and being positioned in about 120* offset relation to each other on a common carrier shaft, means to rotate the cam means whereby the pawls force the frame to move and the roller is forced to move around the outer circumference of the frame to effect a bending action on a tube received between the frame and the pressure plate.
 3. In a tube bending apparatus as in claim 1, the provision of a support shaft carried by the linkage means for the cam and pawl means, a plurality of identical cams, means securing the cams to the support shaft in balanced offset relation, a pawl means being carried by each of said cams, and the different pawl means having fingers thereon of slightly different lengths.
 4. In a tube bending device as in claim 1, the improvement comprising said device being mounted on cam means and having an operative and an inoperative position.
 5. In a tube bending device as in claim 2, the improvement comprising said pawls having a center bore engaging said cam means, re-leasable means urging said pawls to operative positions engaging said gear rack.
 6. In a tube bending apparatus as in claim 2, the provision of a support shaft carried by the linkage means for the cam and pawl means, means securing the cams to the support shaft in balanced offset relation, and the different pawl means having fingers thereon of slightly different lengths.
 7. In a tube bending apparatus as in claim 3, the cam and pawl means being coordinated with each other inrelation to the pitch of the gear rack teeth so that one revolution of a cam will cause the pawl means thereon to advance into engagement with another tooth on the gear rack. 